In manufacturing structurally insulated panels, pressure loads are carried across the surface of platens within building material presses to provide firm, consistent pressure to surfaces of polystyrene structural panels during polyurethane pressurized foaming and curing or during bonding of adhesive materials to insulating elements and or structural elements of building materials.
Typically building material presses cover large surface areas multiple feet wide (or tall) and many feet long. A typical press may be 4 feet wide and 8, 10 or 24 feet long. Other common sizes of presses are 2 feet and 8 feet wide. Besides other sizes used, custom presses of a suitable width built to requirement can be employed. The pressure per square inch from a press may be low but cumulative force over the entire surface is great.
Many low pressure applications require low rigidity platens. The outward pressure from some manufacturing processes is relatively uniform across the surface. As higher pressures are required platens from lower pressure presses deform or break. The current solution is to increase platen rigidity along with pressure increases resulting in more and more massive platens which significantly increase press costs.
Another problem is some manufacturing materials act like fluid during the manufacturing process. The fluid nature of materials such as uncured foaming polyurethane allows flow under pressure to the weakest points of the platen and exaggerates press weaknesses. Typically this results in deformation first forming towards the center of the platen which increases the need to use massive reinforced platens. Without a massive platen made from extremely rigid materials, the pressed material would not remain flat or planar on the surface especially at the center of the panel. One way to restate this is the pressurized material acts like a fluid and seeks ideal pressure vessel shapes resulting in more pressure towards the center of the panel.
Prior art for the manufacture of building material presses includes hydrolic and air ram presses, rigid boxes with steel cabling and screw down locking mechanisms, mechanical screw presses, and vacuum presses. All these presses seek to apply relatively even pressure across the surface of the presses materials. If pressures exceed the strength of the platen to hold the material in place, the platen is reinforced until it is rigid enough to hold.
Recently demand for energy efficient building solutions has created a capacity shortage in the number of presses available. High press costs to add incremental production is constraining industry by slowing capability additions among building material vendors in the polyurethane panel space. To rapidly expand production of these highly desirable and in demand materials a lower cost press is needed.